Integrating Stepwise planner

[teresaqhoang]

Motivation and Context

This PR adds support for Stepwise Planner to enable MRKL style planning in Chat Copilot.
See microsoft/semantic-kernel#1468 for details on how Stepwise Planner works.

• Stepwise Planner will only be called if a plugin has been enabled. This follows the same logic as Action/Sequential Planner.
• Added StepwiseStepView and StepwiseThoughtProcess components to render friendly view of Stepwise thought process in prompt dialog.

Description

If Planner returns with thought process:

If Planner returns with suggested response or information

Specific Changes:

• CopilotChatPlanner class:
  • The planner now includes support for the new Stepwise Planner and StepwiseStep model.
  • The planner now includes bailout functionality, which allows the planner to request additional user input if needed.
• ProposedPlan model:
  • Updated to include a new PlanType called Stepwise.
• PlannerOptions:
  • Updated to include a new StepwisePlannerConfig property.
• ChatMemoryController:
  • Updated to sanitize log input by removing new line characters.
• ExternalInformationSkill class:
  • Updated to use the Stepwise Planner if the PlannerOptions.Type is set to Stepwise.
• appsettings.json file:
  • Updated to include a new configuration section, StepwisePlannerConfig, which includes settings for the Stepwise Planner feature.
• TextUtils file:
  • Added utility function to format text containing \n line breaks into paragraphs.

Contribution Checklist

• The code builds clean without any errors or warnings
• The PR follows the Contribution Guidelines and the pre-submission formatting script raises no violations
  - [ ] All unit tests pass, and I have added new tests where possible
• I didn't break anyone 😄